Answer:
The molar heat of solution of potassium hydroxide = 57.7 kJ /mol
Explanation:
<u>Step 1:</u> Data given
Mass of potassium hydroxide = 4.21 grams
Volume of water = 250 mL
Temperature rise = 4.14 °C
Density = 1g/mL
Specific heat = 4.184 J/g°C
<u>Step 2:</u> Calculate the heat absorbed by water
q = m*c*ΔT
⇒ with m = the mass of water = 250 grams
⇒ with c= the specific heat of the solution = 4.184 J/g°C
⇒ with ΔT = 4.14 °C
q = 250 * 4.184*4.14 = 4330.4 J
<u>Step 3:</u> Calculate moles of KOH
Moles KOH = Mass KOH / Molar mass KOH
Moles KOH = 4.21 grams / 56.106 g/mol
Moles KOH = 0.075 moles
<u>Step 4:</u> Calculate molar heat of solution
4330.4 J / 0.075 moles = 57738.7 j/mol = 57.7 kJ /mol
(Note that the enthalpy change for the reaction is negative because the reaction is exothermic)
The molar heat of solution of potassium hydroxide = 57.7 kJ /mol
